Portable hammer



- G. WILHIDE Oct. 21, 1941.

PORTABLE HAMMER Filed Jan. 9, 1941 2 Sheets-Sheet l GLENN C. WILHID Oct.21, 1941. e. c. WILHIDE PORTABLE HAMMERI 2 Sheets-Sheet 2 Filed Jan. 9,1941 Z9 v ZJ W G MLHI DE 3Wm&

Patented Oct. 21, 1941 PORTABLE HAMMER Glenn C. Wilhide, Baltimore, Md.,assignor to The Black and Decker Manufacturing Company, Towson; Md., acorporation of Maryland Application January 9, 1941, Serial No. 373,746

8 Claims.

The invention relatos to power operated hammers and more particularly tothe type of hammer which is adapted to be hand supported and directed,being electrically driven. V

In.such hammers there is a reciprocating cross head and a.ram connectedto the cross head by resilient means which usually includes a cylinderand piston and a spring which tends to advance the ram which is mountedfor reoiprocation in a guide or sleeve at the lower or remote end ofwhich the bit is mounted in a suitable nose piece according to the usualpractice the upper end of the bit projecting into the path of the ram.

.While the path of.the ram is normally limited by the transfer of itsmomentum to the bit whereby it.is transmitted to the work, it notinfrequently ..happens through inadvertence or through accidentalrelease of the bit or for other reasons that the hammer is operated inthe absence of a bit, or idled. V

Under these circumstances the period of vibration of the ram andresilientmeans, being in accordance With the preferred design of thesetools, equal to the normal period of the stroke of the crosshead andthus synchronized therewith, to increase the impact of the blow, thereis no definite limit to the strokeand in the absence of a bit the ramdescends beyond its normal stroke or path and tends to strike th nose.Under these circumstances, particularly with the larger hammers whichare of relatively high power, there is a tendency to break the barreland nose due to the impact of the hamme against the nose.

this looking device which receives the full blow of the ram is providedwith a resilientspport or cushion Whereby the shock of the blow is absorbed. In the operation of the preferred form of the invention it isalso notable thatthe first elongated stroke Which occurs in any idlingperiod results in looking and holding the ram throughout the idlingoperation and this idling operation is thus rendered harmless.

In accordance with the preferred construction as illustrated, the samebeing subject to variation, the ram looking or holding member is in theform of a heavy split ring having a slight taper. This ring is supportedjust below or near the lower end of the normal stroke of the ram and inits path and the lower end of the ram is formed with a correspondinglyslight taper so that while the ram is adapte d to engage in the lookingring or other looking member and to be clamped thereby so that the ramis held against recoil, it is readily dislodged by the forcing of thebit into the nose in working position, it being understood that lookingtakes place only when the hammer idles or starts to idle in the absenceof a bit. While the cushion may be regarded as mainly to prevent injuryby the shock Some expedients for checking the vibrations and destructivohammering of the ram in idling have been tried but none of them havebeen fully eiective with the larger size high power hammers to Whichreference has been made. With such hammers idling, which is regarded asunavoidable in ordinary use is extremely destructive so that there hasbeen a tendency to limit the size of these hammers on this account as aneX- 'cess sales resistance in the larger sizes Was encountered.

In the improved construction which is found to present a satisfactorysolution of this important problem, means is provided for holding orlooking the ram at the lower end of its elongated Stroke which resultsin idling in the absence of a bit, so that the destruction incident tohammering under these circumstances is prevented. In the more highlydeveloped form of the device Which may be referred to as the preferredform,

of the idling stroke, it also tends to prevent too strong and permanentengagement of the looking elements.

In order to limit the contact between the nose and the ring and toprevent sticking, the tapered porti0n of the ram has been shown asslotted in the direction of the axis.

The looking device including various cooperating parts has come to beknown as an idler.

In the aocompanying drawings, I have illustrated so much of a portableelectric hammer equipped with the idler of the invention as is regardedas necessary for a full understanding of the construction and operationof the device.

In the drawings:

Fig. 1 is a section on the axis of the hammer barrel showing the lowerend of the barrel and guide of a hammer of the type referred to,including the ram and looking member or ring in the preferred form, thering being shown in section.

Fig. 2 is a similar section through the upper end of the sleeve andbarrel, the contained parts including the crosshead and spring being inelevation.

Fig. 3 is a transverse section looking downwardly in the direction ofthe nose, the same being taken on the line 3-3 in Fig. 1.

Fig. 4 is a side elevation of a complete hammer of this type some of theconcealed parts not otherwise illustrated being shown in broken lines.

Fig. is a section similar to Fig. 1 with the idler or looking deviceengaged, the ram being locked in a position below its normal stroke.

Referring to the drawing by numerals each of which is used to indicatethe same or similar parts in the different figures, the hammer as shownin Fig. 4 includes a casing l having a grip 2 and a barrel 3. The casingencloses the usual motor 3 connected by reducing gears 5 to the crank 6which operates a connecting rod I.

This connecting rod is connected at its lower end to a cross head 8,Fig. 2, which operates in a crosshead guide 9.

This crosshead 8 is shown as provided with a hollow piston El whichprojects downwardly into a corresponding and cooperatng cylinder Hformed in the ram IZ, inversion or other rearrangement beingcontemplated.

The ram 12 is mounted to reciprocate in a ram guide or sleeve I4 mountedin the barrel ina manner to be further described.

The piston El in the form of the invention shown is formed at its upperend with a helical spring seat IS which is grooved to receive the upperend of a coiled spring I6 and this spring is coiled in frictionalengagement about the piston H) for its entire length below the springseat l5 bearing at its lower end at ll against the upper end of the raml2, and preferably at a single point or practically so whereby it iseccentrically loaded;

In accordance with the usual practice the piston H] enters a cylinder l3formed in the ram, reversa] of the cylinders or other telescopingarrangement being contemplated.

In the form of the invention shown, the upper end of the sleeve l4 isthreaded at l8- into a corresponding threaded seat or opening in theinside of the barrel at its upper end and the sleeve or guide l4 issurrounded by the usual cooling jacket l9 between the sleeve and thebarrel 3, most of which features and detail-s are known.

In the form of construction shown, the sleeve or guide M is enlarged atits lower end as at and extends downwardly inside a similarly shapedseat or guide 2| formed for the same in the lower end of the barrel.This enlargement provides an internal downwardly disposed shoulder 22 onthe inside of the sleeve M.

The looking member shown in the form of a heavy split ring 24 is seatedin the enlarged an nular chamber 23 in the sleeve or guide |4, the upperend of said chamber being the downwardly disposed shoulder 22. This ringhas its internal surface 25 tapered downwardly from the internal surfaceM of the sleeve M. The taper is of clownwardly reducing tendency andcomparatively slight. The angie oftaper in the form shown is about fourdegrees, all of which minute description is for the purpose of completedisclosure of a construction which is found to, be satisfactory and notfor purposes of limitation. Variation of the ram looking feature is alsocontemplated.

The ring 2 1 is seated on a washer 26 which has a free sliding fit insaid chamber 23 and in turn rests on a resilient cushion shown in theform of a resilient ring or cushion 21 which may be of rubber likematerial being preferably of an oil resisting product as Neoprene or thelike. This ring in the form shown is seated in a per pheral groove. 23encircling the top of the nose piece 29 and open at the top. This nosepiece is, in the form of the invention shown, threaded into or otherwisesecured in the lower chambered end of the guide or sleeve |4 and thecushion ring 21 is enclosed and supported in said chamber 23;

In order to co-operate with the looking ring 2i, the lower end of theram at 30 is formed with a reducing taper Which is preferably of thesame angle as in the internal taper of the ring but in the form shown isof less extent in the direction of the stroke of the ram. In the toolshown the length of the taper on the ram is a little over one half thelength of the taper of the inside of the ring.

In the construction from which the drawings were made, the taper of thering has a length of a little less than one inch and the taper of theram has a length of a little over one half inch, the figures beinginformative as to a satisfactory construction and not for purposes oflimitation. This also applies to the details of construction.

It is also noted that the lower end of the ram 2 including the taperedportion is grooved in the direction of the stroke at 32 to reduce thecontact of the tapered portion of the ram with the internally taperedsurface of the ring whereby the gripping action of the ring inconnection with the ram is reduced. The construction shown in Eig. 1also includes a packing ring or the like at 3|. 7

The operation of this type of hammer has been pretty well explained. Thenormal relation of the parts at the lower end of the barrel is bestillustrated in Fig. 1. In this instance, the upper end of the shank ofthe bit 33 is in normal position, the bit being engaged in the usualmanner with the aperture 34 in the nose piece 29.

With the bit in this position, the hammer being in operation, thecutting end of the bit is essentially in engagement. with the. work orother sufficiently hard object. Under these circumstances the momentumof the ram is transferred to, the bit by the contact of the ram with theupper end 35.. of the bit and the ram steps at or immediately ad-jaeentthe position indica d by sa d upper end o.f: he bit in Eig. 1,.

In Fig. 5, however, the bit, has been remQved a d. the stroke of he.resilien ly mounted ram, being 1q r t a tha o the cross. head du.e tothe r .nt c nne on t ee th mm and cross head, which may be embodiedspring IB and cylinder and piston l.0 and ll and the synchronization ofthe periods of vibration of the cross head and ram carries the lower endof the ram downwardly below its normal stroke and beyond the position otthe upper end of the bit at 35 in Fi l.

The extreme lower end of the ram at 36 being of less. diameter than thecorresponding upper portion 33' of the ring cavity, the lower end of theram enters well into the ring as illustrated in Fig. 5. The ram havingthe taper described or a taper similar to that of the ring and similarlyproporti0hed, the ram becomes locked in the ring and the idlingoperation ceases after the initial idling stroke. Under thesecircumstances the motion of the cross head relative to the ram is takenup by the resilient connection including piston 6 and cylinder H and thespring E6. The spring l-6 however, in the present instance, exertspressure, i. e., thrust instead of tensionand has no eiect When the ramis locked,

silient support of the looking ring 24 by means of the cushion 21, Whichmay be of any suitable resilient nature cr material. This resilientmember which, in the form shown, is protected from direct contact withthe looking ring 24 by washer 25 yields downwardly permitting acorresponding downward motion of the ring 24. This yielding not onlyprevents destruction of the parts including the barrel, the sleeve andthe looking ring and possibly other parts but it tends to prevent tooclose and permanent engagement of the lower end of the ram with saidring 24.

It is of particular importance that when the looking ring and the lowerend of theram are engagedas described and as occurs in the normaloperation of the tool, the ram can be instantaneously and convenientlydisengaged and returned to normal operation by the insertion of bit 33as shown in Fig. 1.

It should also be noted that the illustration Fig. 5 shows the ram atthe instant of impact at the end of the first elongated or idlingstroke, the resiliency of the cushion being sufficient normally toreturn the ring 24 to the position shown in Fig. 1, in which it bearsupwardly against shoulder 22. In Fig. 5 the tapered end of the ram at isin locked position in the ring 24 but both the ring and the ram are inthe position of impact, slightly below the normal locked position inwhich the ring 24 bears upwardly against shoulder 22. This position theyWill instantly assume due to the action of cushion 21. This position isheld until the ram is released as by insertion of the bit.

While the lighter hammers of the low power variety require protectionresulting from the looking device of the invention, it is particularlynoted, as pointed out in the preamble, that the heavier and morepowerful hammers are even more quickly and seriously affected by idlingin the absence of such protection. The injury takes form of breakage anddeterioration of parts due to excess vibrations and hammering of the ramon the nose in the absence of a bit. The looking device herein describedwhich instantaneously checks and holds the hammer at the lower end of itpath on the first idling stroke retaining it until the bit is inserted,completely protects even the most powerful hammers from suchdeterioraticn making it possible to use with reasonable economy andsatisfactory results hammers of the portable electric type of thehighest power that can be constructed within the limit set by therequirement for portability.

I have thus described a single embodiment of the invention, thedescription being specific and in detail in order that the manner ofconstructing, applying, operating and using the invention may be fullyunderstood, however, the construction shown is capable of considerablevariation, the specific terms herein being used descriptively ratherthan in a limited sense and the scope of the invention being defined inthe claims.

What I claim as new and desire to secure by Letters Patent is:

1. A portable power hammer having a reciprocating cross head, a ram,guiding means therefor and resilient means between the ram and crosshead transmitting motion from the ram to the cross head and permittingvibration of the ram relatively to the cross head, means for supportinga bit in the path of the ram, means for checking and holdingthe ram whenit descends below the path of the normal Working stroke as. in theabsence of a bit to prevent destructive hammeringand vibration inidling, said looking means =comprising an internally tapered ringencircling the path of the ram,;the ram being correspondingly tapered toenter said ring, the guide having an annular chamber containing the ringand longerthanthe axial extent of the ring and yielding means supportingthe ring.

2.. A portable power hammer having a reciprocating cross head, aram,guiding means therefor and resilient,means between the ram and the crosshead transmitting motion from the ram to the crosshead and permittingvibration of the ram relatively to the cross head, means for supportinga bit in the path of the ram, means for checking and holding'the ram atthe bottom of the first idling stroke to prevent destructive hammeringand vibration in idling, the same com prising an internally tapered ringencircling the path of the ram at its lower end, the lower end of theram being correspondingly tapered to enter said ring, and the taperedend of the ram being grooved to reduce the surface which contacts thering.

3. A portable power hammer having a reciprocating cross head, a ram,guiding means therefor and resilient means between the ram and crosshead transmitting motion from the ram to the cross head and permittingvibration of the ram relatively to the cross head, means for supportinga bit in the path of the ram, means for checking and holding the ram atthe bottom of its first idling stroke, said means being adapted to holdthe ram when and only when it descends below its normal working stroke,said means comprising an internally tapered ring encircling the path ofthe ram at its lower end, the lower end of the ram being correspondinglytapered to enter said ring and a resilient support for said ring toreduce the shock of the ram in engaging the ring and to limit theintensity of the looking engagement between the ring and the ram.

4. In a portable hammer having a reciprocating cross head, a ram andguicling means therefor, and resilient means between the ram and crosshead transmitting motion from the ram to the cross head and permittingvibration of the ram relatively to the cross head, and means for lockingth ram on its initial idling stroke when it descends below its path,incident to the working stroke, said looking means comprising a heavysplit ring in the path of the ram near the lower end of its normalstroke and encircling said path said ring having a slight internaldownward taper and the lower end of the ram being adapted.

to enter the ring and having a similar taper, both said tapers being ofapproximately four degrees, the ring being mounted to move in thedirection of the stroke and a resilient support for the ring.

5. In a portable power hammer having a cross head and a ram, means forreciprocating the cross head and resilient means between the cross headto the ram transmitting motion from the ram to the cross head andpermitting vibration of the ram relatively to the cross head, means forlooking the ram at the lower end of its first idling stroke, saidlooking means comprising fric tion means in the path of the ram andhaving a. slighttaper in the direction of the stroke, the ram having acooperating tapered friction means,

said frictlon means being timed to eflgage when the ram desoencls belowthe path of its working stroke in the absence of a bit, and a resilientsupport for one said friction means whereby it is free to yield inresponse to the impact of the ram and means for limiting the upwardmotion of said first friction means whereby the ram is locked insubstantially its lowest position, said looking means being adapted forrelease by the insertion of a bit.

6. In a portable power hammer having a cross head and a ram, means forreciprocatng the cross head and yielding means between the cross head tothe ram transmitting motion from the ram to the cross head andpermitting Vibration of the ram relatively to the cross head, lookingmeans on the ram and cooperating locking means in the path of the ramfor looking the ram to prevent harmful vibration of the ram in idlingsaidlocking means being timed to operate when the ram descends below itsnormal working stroke as in the absence of a bit, one sai-d lookingmeans having a resillent support to reduce the impact incident to theengagement of the looking means.

7. In av portable power hammer having a cross v head and a ram, meansfor reciprocating the cross head and yielding means between the ram tothe cross head transmitting motion from the ram to the cross head andpermitting vibration of the ram relatively to the cross head, lookingmeans in the path of the ram and cooperating looking means on the ram,said looking means being normally inoperatve, engageable with saidlooking means when and only when the ram descends below its normal pathin idling, said looking means being mounted for movement in thedirection of the Stroke, and having a yielding support to reduce theimpact of the ram in looking and a stop to limit the movement of thelooking means upward from said support.

8. In a portable power hammer having a cross head and a ram, means forreciprocatng the cross head and yielding means between the cross head tothe ram transmitting motion from the ram to the cross head andpermitting Vibration of the ram relatively to the cross head, lookingmeans on the ram and cooperating looking means in the path of the ramfor looking the ram to prevent harmful vibration of the ram in idlingsaid locking means being timed to operate when the ram descends belowits normal working stroke in the absence of a bit.

GLENN C. WILHIDE.

